Irradiated Glass / Altered Glass / Artificially Purpled Glass
In recent years the practice of altering the color of glass has reached epidemic proportions, and is an increasingly confusing and undeniably damaging aspect of the subject of collecting antique or vintage glassware.
The collecting fields of American antique bottles, fruit jars, Early American Pattern Glass (EAPG), and antique glass electrical insulators have probably been affected the most by this trend.
There are several ways in which glass can be color-altered, but the most common, as well as problematic, and highly controversial, is the use of equipment that sends germ-killing X-rays or Cobalt-60 gamma rays through food (including meat, fresh produce and spices), killing micro-organisms as part of increased safety procedures. This process of irradiation (often called “nuking” by glass collectors) has been rapidly increasing in use in the United States and other countries over the last few years.
Purple (Amethyst) Glass
Authentic purple glass has been made for many years, and has seen periods of rising and falling popularity, particularly as relating to glass tableware. Glass lumped under the term “purple” can range widely from a very pale lavender or lilac, to medium shades of purple, to very deep royal purple, to virtual “black glass” in which the color can only be seen when a very, very thin sliver is held up to a bright light. (Note: Some purple tableware and art glass may have achieved its color from the use of nickel oxide, not manganese which was the main ingredient used in older glass bottles).
Much of the “clear” or “off-clear” glass made during the 1870s-1920s contains the element Manganese, which was intentionally added to the glass “batch” as a decolorizing agent. The manganese helped to “mask” or “neutralize” the effects of iron (a normal impurity in nearly all sands used for glassmaking) that would otherwise result in some shade of light green, blue-green or aqua color in the finished glass. (Note: sometimes the element referred to here is erroneously called “MAGNESIUM” by glass collectors and writers. The element used as a decolorizer is indeed Manganese, NOT magnesium. Those two elements are easily confused because of their similar-sounding names).
Manganese, in somewhat higher quantities, also imparts a purple color to glass. When manganese-containing types of glass are subjected to later irradiation, the glass may turn various shades of purple. These shades may appear as an odd “grape-Kool-Aid” purple, a blue-purple (almost leaning toward a cobalt-blue color in some instances) or a very deep royal purple.
NOTE: Glass containing enough manganese will NATURALLY turn some shade of very light to medium purple after several years of exposure to the rays of the sun. This was frequently termed “SCA” (sun colored amethyst) or “desert glass” by antique bottle collectors especially in the 1960s and 1970s. In most cases the shade of color seen in “desert glass” is quite light or “pastel”. In some cases, after long exposure in the sun, the purple color will become rather dark, as is seen occasionally in bottles and other glass found in old mining camps and “ghost towns” of the old West. The shade of color will depend on how much manganese was in the glass batch (recipe or formula) at the time the bottle was manufactured, in conjunction with the length of time the glass was exposed to the elements.
HOWEVER, the artificial purpling of glass (especially when strong doses of irradiation is used) typically causes a decidedly darker or “peculiar” shade of purple to result. Most ordinary utilitarian bottles in really dark purple shades (with some exceptions) were irradiated to achieve that color.
Although I would agree that sometimes authentically “sun colored” glass can reach a medium/dark shade, IF you find a large number of bottles of various types, all exhibiting the same noticeably dark purple color, being sold in a flea market or antique mall environment, the chances are very good they were not colored by ordinary exposure to sunlight, but by artificial means. (See “Bottle Purpling” paragraph below).
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PURPLE EAPG
There are several fields of glass collecting in which the scourge of artificially “purpling” glass has become really a serious problem, especially to those collectors who have a real interest in the preservation of the history and integrity of old glassware. This includes the field of what is called EAPG (Early American Pattern Glass) . Some of these pieces have been irradiated ( artificially purpled) and then offered for sale at flea market booths and on online auction sites. Such items as water and milk pitchers, spoonholders (spooners), creamers, tumblers, salt cellars, sugar bowls, compotes, cake plates, oil lamps, and other forms of tableware in various patterns of the 1880s-1910s have been irradiated, and are sold to unwary collectors, or casual buyers merely looking for decorator items or something that “catches their eye”. Some of these buyers really couldn’t care less about the provenance or authenticity of the glass, thus compounding the problem. If/when the nuked glass is re-sold years later, the next purchaser typically assumes the glass was made in that color at the glass factory.
Although some purple glass was produced in a few EAPG patterns, very, very little of it was made originally, in comparison to the TREMENDOUS quantities of clear (or an attempt to be as colorless as possible) early American glass tableware.
Bottle Purpling
Another field of glass collecting is the study and collection of antique bottles and flasks. Many of the more common types of clear glass bottles of the 1880-1920 period are now being mass-irradiated and sold at flea markets. If you spot a large number of old purple bottles (or jars) within a particular booth in a flea market or antique mall, you can be fairly sure they have been irradiated, and were originally colorless, or perhaps a much lighter shade of amethyst before being irradiated. Along with the purpled bottles, you might seen bottles in odd shades of brownish-green (such as Coke bottles).
The perpetrators of this type of wholesale altering of glass usually (but not always) do this to a lot of the more unremarkable clear glass bottles such as common druggist, soda, ink, chemical, whiskey and food bottles, sometimes those with no brand name or city on the face, and often examples that are completely “slick” with no markings at all.
It is very common for old purple bottles such as these to be dull and heavily stained with a whitish residue or “sickness” on the surface of the glass. This is a strong indication that the bottles have been dug (the sickness having been caused by long burial and long continued contact with moisture) , were clear (or very light purple) to begin with, and were later irradiated en masse. Contrary to what some sellers might say, there is little reason to believe that these bottles would eventually darken to that degree if they were left in the sun for a thousand years. The process of irradiation is not quite the same as ordinary sunlight, and it is more likely that the glass would not attain this dark of shade of purple if purely “sun-colored” naturally.
Glass Insulators
Some glass telephone insulators, and some bottles which were originally an aqua or light green color may be altered/irradiated to come out a purple color, and in some cases (depending on the exact chemistry of the glass and what ingredients were contained in the cullet used when forming the batch) a peculiar cornflower blue, dull gray blue, or sapphire blue may result.
(To make this even more confusing, a number of types of electrical insulators – as found in the wild – are seen in authentic medium and dark shades of purple, for instance, some of the W.F.G.CO. and W.G.M.CO. insulators from Denver; the AM TEL & TEL CO tolls; the Whitall Tatum CO. No 1; and many of the “Diamond” CD 102 ponies from Canada).
Selenium
Clear glass that was originally decolorized by using selenium as the active ingredient instead of manganese (the use of selenium was particular prevalent in the 1920s and 1930s and later) may turn strange shades of “burnt amber” or “smoky dull dark brown” under irradiation, which are colors virtually unknown in the production of the original glass product. Just for an example: If you find an insulator marked “HEMINGRAY-42” and it is in a dark brown/amber color, it has been IRRADIATED! (No original Hemingray-42’s were ever made in such a color).
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Recently, Coca-Cola and other types of soda bottles have appeared for sale online that have been irradiated, resulting in a peculiar dull “burnt brown” shade. The original “Coke bottle green” or “Georgia green” color (light green-aqua) has been changed to this odd, sickly appearance.
Knowledge of exactly which colors are known in the various types of original insulators can be gained by studying value guides, along with searching for information on various webpages that delve into more detail on this subject. Sometimes, noting the exact embossing variant or arrangement (configuration or orientation of the lettering on the glass surface) on a given insulator can give clues as to whether that piece is verified to exist in that particular color, and/or whether that piece may have had the color altered by some means many years after its original manufacture.
“Stained Glass” / Surface-stained glass (this subject is not pertaining to the more commonly understood context of “stained glass” as relating to architectural or ornamental glass seen in church windows).
Sometimes glass (and this pertains especially to electrical insulators) is surface stained to achieve the appearance of a different color, typically an unusual color completely different from the actual color of the glass. This has become increasingly common on auction sites such as ebay. In many cases the description of the insulator is written in such a way as to deceive or confuse new or unsuspecting collectors who will assume a color is authentic or “all-the-way-through-the-glass” when it is merely a surface coating. A clear glass insulator of a common type with little monetary value may appear to be a much more valuable type by adding a surface coating! The color may be achieved by using some type of glass paint, and sometimes subsequent heating to cause the color stain to adhere more steadfastly to the glass. Thus a “one dollar” insulator may be wrongly assumed to be worth much more because the color is perceived to be “rare”.
Most “serious” insulator collectors frown on this practice and encourage other hobbyists to learn more about what they are actually buying. Some online sellers may imply in their descriptions that this practice of surface-staining is ethical or highly to be praised, and that the buyer is just obtaining an unusually colored insulator to display in their window for mere decoration.
There may be nothing intrinsically “wrong” with that, but the problem comes when the piece is RESOLD and the next person who gets it may have NO IDEA about it’s provenance or whether or not the color is authentic and original. The insulator may be sold for a much higher price than it is worth if the seller and/or the buyer doesn’t understand that the color has been altered.
Here are some webpages that I would strongly recommend for more detailed information on this subject:
Artificially purpled Early American Pattern Glass:
http://www.patternglass.com/sunpurple.htm
Webpages concerning fake and altered glass insulators:
https://www.nia.org/general/g_natpt_fakes.htm
https://www.myinsulators.com/magicmist/warning.html
Fake colors in insulators:
https://www.insulators.info/books/fake/appendix1.htm
Bottle colors:
https://sha.org/bottle/colors.htm#Purple%20to%20Amethyst
Bottles — Irradiated Glass, the Color of Greed:
https://dumpdiggers.blogspot.com/2008/01/irradiated-glass-amethyst-color-of.html
The Chemistry of Purple Glass – by Rick Baldwin
https://ohiobottleclub.org/wp-content/uploads/2018/07/THE-CHEMISTRY-OF-PURPLE-GLASS.pdf
A nice reference book illustrating lots of purple glass: Purple Glass: 20th Century American & European, a Schiffer Book for Collectors, (Leslie Pia, Ed Goshe and Ruth Hemminger) illustrates a wide variety of purple tableware and art glass, all (or virtually all) believed to be authentic and as originally made.
Please click here to go to my Home Page.
Click here to go directly to the Glass Bottle Marks pages (listings of marks used by glass companies / manufacturers on bottles and other glassware).
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I just want to say “Thank you” for putting all this info online. I recently found a 1910 Hazel-Atlas half gallon jar that has a nice shade of lavender, and some Qt Duraglas milk bottles with their metal caps at a thrift store. I learned about both companies from this website!!! Thank you again and God Bless you and the United States of America!
Hi Lisa,
Thank you very much for your kind words! I’m glad to be of help! And may God Bless you as well!
David
Hello David,
When I was beachcombing, I found a Vaseline jar that was a dark brownish-amber color. It is a machined screw top bottle, approximately 2 1/2 inches tall, and says “Trade Mark/Vaseline/Chesebrough/New York.” and has the number 6 on the bottom. Is this irradiated and what approximate decade was it from?
Thanks,
Mack
Hi Mack,
No, it isn’t irradiated. Vaseline jars were made in both clear and amber glass. Please see my article about Vaseline jars here: Chesebrough Manuf’g Co / Vaseline Jars
I can’t be sure exactly how old your jar is, but the screw-top jars were made for a long period of time. Since it has raised (embossed) lettering, possibly it could date from the 1920s-1950s period. The “6” is a mold number and tells us nothing about age. Later jars, probably after the 1950s, had a paper label but no raised embossing on the face of the jar.
Hope this helps,
David
Prior to her death at 72, in 1972, my Grandma Ruby lived in Tucson Estates. She had a collection of what she called her purple glass. It was outside in the sand. She’d go out daily and turn it so it colored evenly. (I’d also seen a tarantula go inside a pipe out there and she turned the pipe, too – sent it back where it came from.)
I was under 10 yrs old and thought it was so silly, until she showed me pieces that were “done” and in the trailer. The lovely lavender shades, with a little variation on the shade, was so beautiful. Thanks for a wonderful read, buyer beware.
Hi Sandy,
Thanks for your comments! What a great story. Coincidentally, I used to live in Tucson when I was a youngster. We lived in the southern part of Tucson, on Drexel Road near Alvernon Way, but moved away in 1974. I haven’t been back for 45 years, but I miss Arizona and the West in general.
From what I understand it was quite a popular “fad” in the late 1960s and early 1970s to “sun” old glass that was suspected of being able to turn some shade of purple. Of course, only certain types of clear glass would turn – it has to have some manganese in it, which usually meant older bottles pre-1920. Take care and thanks again!
David
As a chemist and “color specialty” collector and researcher of insulators and bottles, I have written articles and presented seminars and displays on the subject for over four decades. To complement the subject matter discussed herein, here is a link to an earlier article, which I authored, that elucidates the chemistry of “purple glass”…whether by natural sun-coloring or by artificial means utilizing more energetic ionizing radiation: https://ohiobottleclub.org/wp-content/uploads/2018/07/THE-CHEMISTRY-OF-PURPLE-GLASS.pdf
Hi Rick,
Thanks for the link! I appreciate the great information and all your work on the subject!
Take care,
David
Thanks David. I routinely send my article to Insulator collectors, etc. on social media who express an interest in a semi-technical explanation of the chemistry of purple glass. If you think that such would be relevant, feel free to add the link that I included in my response to your ” formal” listing of webpages at the end of your document. The subject matter seems to resurface periodically.
Rick, I will be more than happy to do that. Thanks again!!
David
Hi David,
Reversal of “nuked” glass has been achieved with 100% success on both machine and mouthblown bottles. I purchased both straw colored and deep purple vaseline jars on Ebay several years ago and after a discussion with Matthew Knapp over the process I sent them to him so that he could put them in his kiln see if reversal back to their original color was indeed possible. The experiment went perfectly and both bottles were reversed back to their natural clear color. After that he did an “irradiated” purple blob for a friend, as well as a historic flask for another, and like with the vaseline jars all the bottles returned to their original state. Here is the written report from Matthew Knapp regarding the experiment, which was also printed in Antique Bottle & Glass Collector magazine in 2014 along with photos of the process and bottles…
“Can the coloring effects of irradiated glass be reversed?
We know that the color of glass can be changed by exposing it to high energy radiation. Clear glass containing manganese will turn purple and clear glass containing selenium will turn a grey/amber. A number of sources have reported that this coloring effect can be reversed by exposing the glass to high temperature. Is this truth or myth?
We are not aware of anyone documenting this process. We will attempt to do an experiment and document the outcome. The first thing we need are some test subjects. Jim Eifler generously provided two sacrificial bottles. They are early 20th century machine blown Vaseline jars. One with manganese coloring and one with selenium coloring. Both have been heavily irradiated, most likely from gamma radiation in a medical waste sterilization plant.
According to various scientific sources the color change occurs when the high energy radiation forces electrons in the glass atoms to higher valence orbits. Since most of color reflection/refraction happens in these higher orbits color change can occur. The new electron orbits can be stable or metastable depending on the energy and the chemical composition of the glass. Metastable changes may revert over time. Bringing the glass above its transition temperature (also known as the annealing temperature) should allow the energized electrons move back to more normal positions.
Now that we have some glass to test we need a way to get them really hot without destroying them. If we just use a torch the glass will heat and cool unevenly and stresses will destroy the glass. To heat and cool in a controlled manner we will use a glass kiln. Hobby kilns are used for making art glass items. It can ramp the temperature up, hold it, and take it back down so the glass wont experience thermal shock.
Next we have to make a couple assumptions. We will assume the glass is soda ash glass. That means it should have a transition point around 930F° and a melting point at about 1500F°. The trick is to bring the glass above the transition point (where the amorphous solid becomes a metal) but keep it below the melting point so we don’t end up with a blob of glass. The melting point may be lower since we are re-melting pure glass. We decided to take the glass to 1100F° to make sure we exceed the transition temperature. The kiln is programmed to ramp up to 1100F°, hold for 15 minutes, ramp down to 700F° (below the annealing point, then turn off. The temperature ramps up about 200F° every 30 minutes.
The kiln takes much longer to cool down than to heat up. It takes about half a day to treat a bottle but many can fit in the kiln at the same time. The bottle was turned back to its original clear color, so manganese irradiation changes are reversible.
Next the selenium bleached bottle was heated, it turned it back clear with no trace of color. We can conclude that irradiated glass can be restored to its original blown color by the act of re-annealing the glass.
This may prove useful in cases where rare bottles have recklessly been irradiated, for instance people who irradiate whole batches of glass not knowing what is common or rare. It can also restore items that have been color modified to perpetrate scams. An example of this would be irradiated Bromo Seltzers in odd colors, or the early Historical Flask from collector Stephen Atkinson. We were also successful in returning it from the irradiated ‘brownish stray’ color to it’s original color without damaging it.
A few interesting related questions have been asked. They will be answered here.
Q. Will a naturally sun colored amethyst (SCA) bottle turn back to clear?
A. Yes, since the UVB from the sun is causing the same effect as the man-made radiation.
Q. Will odd colored (non-irradiated) bottles changed color?
A. No, since they are the color that they were after the first annealing , a second annealing won’t affect the glass color.
Q. Will a microwave do anything to a bottle?
A. Not if the bottle is below the transition temperature when you put it in the microwave. If it is above that temperature then either the microwave will burn up or the bottle will start melting since the microwave will see it as a metal object.
Q. Is it safe to re-anneal early 19th century glass?
A. Not in many cases. If the glass contains cracks, pot stones, annealing fractures or stresses, bruises, etc, the reheating could cause stresses that a bottle wouldn’t survive.”
Regards,
Jim Eifler
Hi Jim,
This is SUPERB information! I really appreciate your posting this for us! Thanks a lot!
~David
My pleasure, the theory had been discussed years ago in an article from the 1970’s that I had read, but the experiment had not been carried out using bottles as of yet that I could find online, which led to Matt and I discussing him using his kiln for testing. His knowledge in chemistry is very strong, and he carried it out perfectly, it’s good to know because someone may have a rare bottle that has been “nuked” that they can have returned to it’s original state. Thanks for all you do with your great site… Jim
Thanks again Jim!
David
I would like to know if Glassware made in a factory can also be reversed, like Fostoria and Cambridge and Heisey glass, most all their glass in clear will turn purple and I would like to know if that too can be reversed. Thank you for reading and I hope to hear back from you soon. I hope you will send me an email,and maybe if there is a site that people can go to and see how this is done.
Hi Frederick,
I can’t say with certainty, but my understanding is that the purple color can be reversed, at least to some degree, in SOME cases, in some types of (originally clear) glass that has turned shades of purple over time, either from sunlight or artificial irradiation. Notice I say “SOME”! BUT the process is risky, involving very slow, gradual heating to a high temperature in an oven, over a number of hours. And it may or may not have any effect depending on the piece involved. The possibility of breakage is always present. There might be other ways. I am not sure about this. Personally, I would NOT recommend any effort to try reversing the color changes, but that is only my own opinion. Thank you for writing!
David
To followup on David’s accurate and cautious reply concerning the thermal reversal of purple glass, most experimentation has been performed with inexpensive early soda-lime “bottle” glass, primarily to address questions posed in the bottle and insulator collecting hobbies. As Fostoria, Cambridge and Heisey all started production in the latter 1800’s, they most likely also utilized manganese as a decolorizer for their early clear glass items, up until 1917 when the supply of manganese was cut off by Germany. Thus, it is possible that their purple or sun-colored glass manufactured during this early time period could also be altered by thermal treatment…but, as pointed out, there are many variables associated with the glass chemistry and manufacturing process that could affect the result of such. As these three companies made more expensive and higher quality glass items, their glass formulations might not respond to thermal treatments as the cheaper glass formulations would.
Hi Rick,
Thanks very much for your insight!! Take care,
David
The experiments have been on glass as late as the early machine made era (1915), as well as with blob top mouth blown beer bottles from the 1880’s and with a 1830-40’s aqua historical flask that had selenium used in it’s production, that when irradiated gave it an odd straw color. All attempts have been successful with zero failures so far….
Hi James,
I know this is addressed specifically to Rick, but may I interject as well….. can you define exactly what you mean by “successful”? Are you saying that the irradiated flask with an odd straw color was returned to it’s original aqua color by heating? Also, what color were the circa 1880s beer bottles, before and after? Can you provide some sources that give more detail on the specifics of these cases? Thanks and take care,
David
Hi David, the historical flask was turned back to it’s original pale aqua using the same method in the same kiln, the blob top beer was returned to it’s original clear color. I don’t have a clue how to attach pics or I would…
Hi James,
Thanks a lot for your info. I’m sorry to say my site is not set up to accept pictures uploaded directly from readers, but I will contact you directly from my email address. Thanks!!
David
When you contact me I’ll attach the pics David… Jim
Hi, I read this article with interest. As a 42-yr glass maker and a 48-yr collector of old glass, I have a fair bit of experience within those communities regarding glass chemistry and faking. Firstly, the best way to determine if a glass contains manganese is with a UV light. Even aqua examples will glow a milky green colour under UV light. Secondly, fakers have been altering manganese glass with UV “purpling boxes” and also exposure to radiation. Irradiated manganese glass typically produces a rich grape purple regardless of original colour, and UV exposed manganese-containing clear glass produces the amethyst hues. Unfortunately fakers have managed to tweak radiation exposure to produce just a slight change in colour, where the first attempts were over-exposed and suspiciously dark and therefore easily detectable. Both forms or colour altering can be reversed by heating the glass to 1000f to reveal the original colour at the time of manufacture.
Hi Mark,
Thank you very much for your insight and comments! They are very helpful!
Best regards,
David
Hi there! I know that purpling antique glass is a controversial topic (obviously), but I feel I must speak out as a collector. I started hunting for old bottles back in the early 80s with my Dad in the ghost towns and mining camps of the western U.S… I can say that DEFINITELY WITHOUT ARGUMENT that it IS POSSIBLE for old clear glass to turn DEEP amethyst in the NATURAL sunlight!!! I have come across several old bottles and jars over the years that turned a beautiful DARK purple by nothing more than good old sunshine! To say that ALL deep amethyst glass has been artificially irradiated is absolutely ludicrous! The amount of manganese that was added to any given batch of glass (prior to 1914), was haphazard to say the least. Some glass when exposed to ultraviolet rays will only slightly purple to a faint pink tint, while others will turn the deepest royal purple. Also the amount of time the glass has been exposed is also a factor… I have set clear glass bottles by on my window sills, and within two weeks they have already begun to purple! I have NEVER artificially irradiated any antique glass using gamma ray bulbs, etc… So the big question for collectors is then, ‘TO PURPLE OR NOT TO PURPLE.’ Anyone that has ever visited an old mining camp or ghost town in the west has certainly noticed the beautiful “desert glass” as it used to be called, scattered about, in every hue of purple imaginable!
As collectors we need not forget that beauty is truly in the eye of the beholder (or buyer) for that matter, and we can’t make assumptions regarding how something came to be, as long as we are honest about it.
Best regards,
Steven F
Hi Steven,
I will agree that sometimes (because of the amount of manganese in the glass batch) some “desert glass” bottles may turn a fairly dark shade of purple. I have re-edited my article slightly, and included the note that *sometimes* bottles that were only sun-colored may reach dark shades of color. However, I will stand by one of my main points, which would be this observation: If you run across a large accumulation or collection of dark purpled glass for sale by one specific dealer at a flea market or antique mall, you can be pretty certain they were irradiated. I have seen this a number of times at various venues in the Midwest. In all cases, the glassware had been irradiated, and there was a mix of bottles, jars, flasks, and maybe a few insulators or other items such as lamps or other EAPG mixed in the inventory that were not in their original colors. Thanks very much for your post. I appreciate your thoughts!
~David
Maybe you could enlighten me about a compote I bought. It appears to be mid century and is a clear, pale purple (lilac?). The weird part is that it glows bright green under a black light! I thought uranium glass was usually green or yellowish. Any ideas about what is going on?
Robin, I don’t know if I can be of any help, but can you email me a pic of the compote? My address is listed on the right hand bottom corner of the page.
Best regards,
David
Hi there Robin-I believe the compote you have is “neodymium” glass? Another name for it is Alexandrite. Neodymium is a rare earth metal used to color class and it changes cplor under different types of lighting. I’m a sea glass collector and Neodymium sea glass is a really rare & special thing to find. So is sun purpled maganese glass but sea glass collectors frown upon anything altered manuallty and not by mother nature. Neodymium glass was made to be that color.
Hello,
Obviously, I have a lot to learn… I often joke that I’d buy a broom if it were purple — That’s how much the color appeals to me. My purple bottle collection is at 31 as of right now, but what I gather from your article is, they are all fake? Or, they actually are antique bottles made between 1880 and 1920, but they’ve been altered intentionally by someone to dupe people like me?
Hi Angela,
I know this subject is very confusing, and there is a lot of misinformation out there. All I can suggest is for you to do A LOT of reading, and don’t make any hasty decisions on buying purple glass. Yes, most (BUT not all) old, handmade PURPLE glass bottles have been irradiated IF the color is fairly dark, since the original color was likely clear (or with a faint green or aqua tint).
(The color of some irradiated bottles will gradually fade over time, if left out in the sun for several months. You might experiment with that, if you are able to have a place to safely “sun” some bottles outside.)
I am assuming most of the bottles in your collection are old (so in that sense they are NOT “fake”) but they have been irradiated to change the color from clear to some shade of purple. If you can, please contact me through my email address (lower right corner of any page on the site) and send me some pics of the bottles.
Thanks, David
All right bud I got one problem with you and what you’re saying they’re fake glass changing colors green purple midnight all this b******* that you keep talking about like you know what you’re actually talking about I don’t think you know crap. yeah they make s*** in a certain color you know what there’s nothing fake about it,……….and all that you know and what you said downgrading something that’s rare or unique are fake I think that’s crap and I think what you’re saying is crap just cuz you’re not made right what you say doesn’t mean crap you are a fake you don’t understand anything I realize that now I read your comments on everything and I think you are an idiot. Aged glass patina makes things different that’s what makes them rare you act like people are making them to make them rare and more valuable I think that is the most idiotic thing I have ever read thanks happen naturally that makes him a fake things change colors through age that makes them unique patina is a natural occurrence it does not make it fake takes years to make something change its color like that . And it takes an idiot to actually say the bulshit he just said just because it’s not in its original state does not mean it’s a fake
Hi Dan,
Since this is a free country (so far), you are welcome to say and believe anything you want to. I will admit that there are many purple bottles, jars and other glassware that were made in a purple color (to begin with) and have always been that color from the beginning. They are NOT fake. But this article isn’t really about that. I am referring to the types of glass that have been changed by irradiation to a different color than what they were when first made at the factory.
“Patina” is a whole different ball game. Glass with a ‘sick glass’ Patina, like “Benicia Glass” can have that beautiful rainbow color, sorta like gasoline sheen on a mud puddle. Not sure what you mean by “patina” but this article isn’t about glass with a patina, but a color change that goes all the way through the glass. “Patina’ is just a surface change.
Most of the altered-color items (such as insulators, bottles, EAPG kerosene lamps) are not fake……. yes, they are real, original glass items, but they have had their original *color* changed. “Fake” is a word that is used by many people with a lot of slightly different definitions. Collectors who like to know how old their glass is, and what the original color was, might be inclined to call an altered-glass item a “fake” even though, technically, it is real. Just the fact that the color is not “original” is enough to have it classed as a “fake” by some collectors.
~David
I found a dark amethyst double safety jar at an antique store. I’m guessing it was irradiated to be this dark? It caught my attention as it was so dark. They were asking 70$ so I thought I’d do a bit of research here first! I wasn’t aware of irradiating old glass!
Hi Darlene, and I am glad you checked out my article. Yes, it is an irradiated jar. Practically NO fruit jars were made in purple/amethyst glass, so we can be sure the color has been changed by artificial means. Take care,
David
I have heard there is a process now to reverse the nuking, resulting in the glass being returned to its original state. Have you heard this as well, and if so, how does one do this?
Jack,
From what I have read or heard, whether any changes can even be effected, it will depend primarily on the glass formula/recipe. So many variables are at stake when glass is being made. In some cases a reversal, either partial, or nearly complete, might be accomplished by slow heating in an oven, or in some cases after several months of being left outside in ordinary sunlight. I don’t have enough solid information to elaborate further, and I can’t claim to be an expert on the subject of nuking. Perhaps someone more conversant with this will chime in with more feedback.
David
Thank you for the informative site! I collect sea glass and selenium can also create “sun yellow” pieces, which are pale or straw colored from exposure to sunshine.
are artificially purpled artifacts more valuable than the normal colored one?
That’s a matter of opinion, but in my view, no. Their authenticity as historical objects has been compromised by color alteration. There is a false perception by the average flea market shopper that they are worth more, but that is because of the prices of such items being asked by unscrupulous dealers, and the unknowing public who is willing to pay more for those items, having little or no background knowledge about those colors and how they were achieved.
David
Here’s a current eBay auction with an altered Ball jar and my contact with the seller to which I received no reply. eBay Item No. 141152627582 I tried to be nice by saying that these can add to a collection; but they’re only a peculiarity and they are not worth what this jar is bringing.
“Dear t****b,
I would like to share with you that Ball never made this jar in Amber or Olive Green. This jar has been zapped or exposed to a strong radiation source(probably industrial in nature). This jar was made from 1923-1933 without the underscore. It was discovered, in times past, when jars were stored after use, upside down on fence posts, that the clear glass would turn amethyst over the years after exposure to UVA, UVB radiation from the sun. So, people whom have access to a radiation source expose numbers of clear jars hoping to hit the jackpot with purple/amethyst jars (they’re usually much darker); in that process some turned a type of amber color and they’re being sold as unique/rare Ball jars when that is not the case. I don’t think there’s any evidence that jars ever turned amber from sun exposure. It’s been reported that these zapped jars can lose the color when exposed to heat or microwave; but I don’t know if that is true. These can add to a collection.”
Thanks Fred. These jars that are being “nuked” are a scourge on the glass-collecting hobby. It certainly confuses many newer collectors who are not sure about the history/authenticity of a particular piece.
~David
Thank you very much, Ken! Great article….. and yes, I should have explained in better detail that glass containing selenium (esp. common during the 1920s-1940s era) often has a faint yellowish, “straw” or “peach” color (for example, a lot of the insulators made by Whitall Tatum during that time period) and so they may end up assuming that weird “burnt amber” or ugly dull brown color after being subjected to irradiation. ~David
Does anyone know about Hemingray insulators? I have 2 that are a teal color it says made in U.S.A. It also has “No 20” on it.
Mary, just google “Hemingray insulators” and you will come up with lots of websites about them. Try checking out Hemingray.info and others. The “No 20” style is classed as a “CD 164” in the “CD” (Consolidated Design) system of identification used by insulator collectors. The Hemingray No 20 is a very common style.
David